Herpes Simplex Virus 1 (HSV-1) Reactivation in Critically Ill COVID-19 Patients: A Brief Narrative Review

Abstract

Systemic or pulmonary reactivations of herpes simplex virus 1 (HSV-1) have been reported in critically ill patients with COVID-19, posing a dilemma for clinicians in terms of their diagnostic and clinical relevance. Prevalence of HSV-1 reactivation may be as high as > 40% in this population, but with large heterogeneity across studies, likely reflecting the different samples and/or cut-offs for defining reactivation. There is frequently agreement on the clinical significance of HSV-1 reactivation in the presence of severe manifestations clearly attributable to the virus. However, the clinical implications of HSV-1 reactivations in the absence of manifest signs and symptoms remain controversial. Our review aims at providing immunological background and at reviewing clinical findings on HSV-1 reactivations in critically ill patients with COVID-19.

Keywords: COVID-19; HSV; Herpes simplex; ICU; Pneumonia; Reactivation; SARS-CoV-2.

Fig. 1

Simplified, potential immunological background of HSV-1 reactivation in critically ill patients with COVID-19. HSV-1 herpes simplex virus 1, IFN-I type 1 interferon, IL-1 interleukin 1, IL-6 interleukin 6, NK natural killer, SARS-CoV-2 severe acute respiratory syndrome coronavirus 2

Fig. 2

Frequency of HSV-1 reactivation in critically ill patients with COVID-19 according to current literature. COVID-19 coronavirus disease 2019, HSV herpes simplex virus